The specific objectives of my research proposal are as follows: 1. To examine the following aspects of GABA neuron differentiation in dispersed cell cultures of rat embryo or neonate hippocampus, diencephalon, midbrain, and especially cerebellum: a. location and density of GABA binding sites for high and low affinity processes; and their relationship to Na,K-ATPase sites. b. role of Na-ATPase and Na,K-ATPase in high affinity uptake of GABA by glial cells. c. ascertain whether low affinity uptake of GABA by GABA neurons occurs by facilitated diffusion. d. role of membrane phospholipids in differentiation of the GABA uptake process. e. how membrane protein patterns change in GABA neurons. f. the role of synaptic activity in the maintenance of synapse components using bicuculline as a probe. 2. Isolate and characterize the binding and translocation molecule(s) involved in presynaptic uptake of GABA. The methods to be used include cell culture, radioautography, fluorometry, gel electrophoresis, affinity chromatography, light and electron microscopy and preparative and ultra-centrifugation.